不太明白你的意思,是二个多项式通分同分母吗?
(x+4)/(x^2+4x)
=(x+4)/[x(x+4)]
=1/x
=(x-2)/[x(x-2)
(x-5)/[x(x-5)-2(x-5)]
=(x-5)/[(x-5)(x-2)]
=1/(x-2)
=x/[x(x-2)]